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Bone microstructure of the Upper Cretaceous theropod dinosaur Troodon formosus

1993; Taylor & Francis; Volume: 13; Issue: 1 Linguagem: Inglês

10.1080/02724634.1993.10011490

1937-2809

David J. Varricchio,

Amphibian and Reptile Biology

ABSTRACT The bone microstructure of three third metatarsals and two tibiae of differing sizes from Troodon formosus was examined. Bone in T. formosus passed through three ontogenetic stages: rapid fibro-lamellar, moderate lamellar-zonal, and slow avascular lamellar growth. Highly-vascularized fibro-lamellar bone accounted for the majority of growth, with adult size possibly being reached in 3 to 5 years. No significant growth occurred after T. formosus reached a body weight of roughly 50 kg (femur: tibia length 310:425 mm). Abundant vasculature together with dense Haversian bone suggests T. formosus had a relatively high metabolism. Other gross morphological features (large brain, large eyes, cursorial adaptations including high tibia: femur ratio) would indicate T. formosus was very active and possibly endothermic.